Sulfurospirillum, widely distributed in natural environments, is a class of anaerobic microbes with the ability to reduce sulfur and sulfur oxides. Some species of the genus can make use of tetrachloroethylene and trichloroethylene, the organochlorine pollutants which are common in the global subsurface environment, as electron acceptors. This metabolic mode has also been called organohalide respiration.

In the recent studies led by researchers of the Environmental Microbial Ecology Team of the Institute of Applied Ecology (IAE), Chinese Academy of Sciences (CAS), the researchers isolated two organohalide-respiring Sulfurospirillum strains in soil samples from a contaminated site, and designated them ACSDCE strain and ACSTCE strain, which were able to grow under culture conditions as low as pH 5.5, and dechlorinate tetrachloroethylene to cis-dichloroethylene and trichloroethylene, respectively.

The researchers systematically carried out multiple classification and identification research focusing on whole genome sequencing, comparative genomics analysis, phenotypic and physicochemical characteristics analyses. They found that ACSDCE and ACSTCE strains, through lateral gene transfer, may acquire genetic components that are related to organohalide-respiring process, such as the reductive dehalogenase gene, and that their ability to tolerate low pH environments may be due to having genes encoding urease in the genome. ACSDCE and ACSTCE strains were similar to most Sulfurospirillum strains in phenotypic characteristics, but were unique in substrate utilization, phospholipid fatty acid composition and optimal growth conditions. Through cooperative studies, the researchers classified the two strains as a new species in the genus Sulfurospirillum and designated it Sulfurospirillum diekertiae.

These study results, published in the papers listed below, have enriched our understanding of the physiology and function of Sulfurospirillum, which will become important microbial resources for bioremediation engineering.

1. Jin H, Huo L, Yang Y*, Lv Y, Wang J, Maillard J, Holliger C, Loffler FE*, Yan J*. 2023. Sulfurospirillum diekertiae sp. nov., a tetrachloroethene-respiring bacterium isolated from contaminated soil. Int J Syst Evol Microbiol, 73: 005693. https://doi.org/10.1099/ijsem.0.005693. 

2. Yang Y*, Schubert T, Lv Y, Li X, Yan J*. 2022. Comparative genomic analysis reveals preserved features in organohalide-respiring Sulfurospirillum strains. mSphere, 7: e0093121. https://doi.org/10.1128/msphere.00931-21. 

3. Yang Y, Huo L, Li X, Yan J*, Loffler FE*. 2021. Complete genome sequence of Sulfurospirillum sp. strain ACSDCE, an anaerobic bacterium that respires tetrachloroethene under acidic pH conditions. Microbiol Resour Announc, 10: e01360–01320. https://doi.org/10.1128/mra.01360-20. 

4. Huo L, Yang Y, Lv Y, Li X, Loffler FE, Yan J*. 2020. Complete genome sequence of Sulfurospirillum strain ACSTCE, a tetrachloroethene-respiring anaerobe isolated from contaminated soil. Microbiol Resour Announc, 9: e00941–00920. https://doi.org/10.1128/mra.00941-20 

5. Yang Y, Cápiro NL, Marcet TF, Yan J, Pennell KD, L？ffler FE*. 2017. Organohalide respiration with chlorinated ethenes under low pH conditions. Environ Sci Technol, 51: 8579–8588.https://doi.org/10.1021/acs.est.7b01510.